- Non-recovery meaning that the animal gets sedated before being exposed to the experimental procedure as well as the animal being put down while still being sedated. Therefore, the animal will only experience discomfort when being sedated. This is considered the mildest form of animal testing.
- The mild severity means that the animal is conscious during parts or the entire experiment but the degree of impact is not considered to be particularly harmful. Examples of this include blood tests and injections, introducing substances into the body.
- The moderate severity causes the animal to experience transient but moderate pain, suffering or distress. Examples of this includes testing of drugs that gives moderate side effects, starvation in more than 48 hours (for rats) , chemotherapy or radiation, cancer that has an impact on the animal or restricted movement in an extended period of time.
- The severe severity means that the animal experiences a great amount of pain, suffering, distress or significant weakening. Examples of this include a vaccine test which can lead to death for some animals, radiation that destroys the animal’s immune system, electric shock, a prolonged restriction of movement or models with progressive lethal diseases.
Finding dead animals in their stables can occur. In such an event, the animal have by definition experienced a severe severity – unless the death of the animal is known for certain and it is possible to prove that the animal have experienced less severity.